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Chemical firms back depolymerization

The plastics recycling method is gaining traction as an alternative to mechanical recycling

by Alexander H. Tullo
September 27, 2018 | A version of this story appeared in Volume 96, Issue 39


A photo of broken polystyrene foam board.
Credit: Shutterstock
Polystyrene waste is difficult to recycle.

As they tackle the problem of plastics recycling, chemical companies are exploring what depolymerization has to offer.

Ineos Styrolution has formed a partnership with two Canadian firms, Pyrowave and ReVital Polymers, to depolymerize polystyrene. Separately, Indorama will create a joint venture with another Canadian firm, Loop Industries, to commercialize technology that turns polyethylene terephthalate into the monomers dimethyl terephthalate and ethylene glycol.

The Styrolution partnership will use technology Pyrowave developed to break down polymers using microwave radiation. The start-up plans to roll out the technology in on-site units that process 400 to 1,200 metric tons of plastic per year. It already operates one such machine in Montreal.

ReVital, a plastics recycler, plans to install the technology at its site in Sarnia, Ontario. The firm will process waste from local residents and institutions. ReVital Chief Commercial Officer Keith Bechard says the technology can pave the way for more recycling of polystyrene “regardless of color, food residue, or odors.”

This isn’t Styrolution’s first such partnership. In April, the firm said it might deploy depolymerization technology from Agilyx at one of its plants. Agilyx operates a facility in Tigard, Ore., that makes styrene via pyrolysis.

Indorama and Loop, meanwhile, plan to build a plant based on Loop’s depolymerization process by early 2020. Loop won’t say much about the plant other than that it will be in the eastern U.S.

Loop also has agreements with L’Oréal, Evian, and Gatorade.

Brian Riise, president of Sustainable Materials Recovery Group, a consulting firm, says chemical recycling’s ability to deal with contamination is its main advantage over mechanical methods that sort plastics and melt them down. “If you have a lot of contamination, there are ways to remove that contamination in a chemical process,” he says.

For polystyrene, the result is a pure monomer that can be polymerized into polystyrene for food-contact applications. For polyester, chemical recycling can treat complex materials such as carpeting, which has pigments and other contaminants.

The drawback of chemical recycling, Riise says, is that it requires more energy than mechanical methods.


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